#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int arr[20] = { 0 };
	arr[0] = 1;
	arr[1] = 1;
	for (int i = 2; i < 20; i++)
	{
		arr[i] = arr[i - 1] + arr[i - 2];
	}
	double m = arr[18] * 1.0 / arr[19];
	printf("%.3lf",m);
}